The gear elements and clutches of an automatic transmission are selectively engaged and disengaged in different combinations to transfer input torque from an internal combustion engine to a transmission output member. The clutch associated with the current speed ratio is referred to as the off-going clutch, while the clutch associated with the desired post-shift speed ratio is referred to as an on-coming clutch. To properly execute an upshift or downshift maneuver, a transmission controller requires detailed knowledge of the return spring pressure for each clutch. While a calibrated return spring pressure is typically stored in memory when the vehicle is first produced, over time the actual return spring pressure may vary from the calibrated value.